package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisConstants;
import com.hmdp.utils.RedisData;
import com.hmdp.utils.SystemConstants;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;

import java.time.LocalDateTime;
import java.util.*;
import java.util.concurrent.TimeUnit;
import java.util.stream.Collectors;

import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {

    @Resource
    private StringRedisTemplate stringRedisTemplate;

    @Resource
    private CacheClient cacheClient;


    @Override
    public Result queryById(Long id) {

        //调用防止缓存穿透的查询店铺方法
      //  Shop shop = queryWithPassThrough(id);
        Shop shop = cacheClient
                .queryWithPassThrough(CACHE_SHOP_KEY,id,Shop.class,this::getById,CACHE_SHOP_TTL,TimeUnit.MINUTES);

        //利用互斥锁解决缓存击穿 --》 某个高并发的Key失效，且该Key的业务复杂获取时间长，导致数据库压力大
       // Shop shop = queryWithMutex(id);
        if (shop == null) {
            return Result.fail("店铺不存在");
        }
        return Result.ok(shop);

    }

    /**
     * 通过添加互斥锁 实现高并发的情况下 避免出现缓存击穿问题
     * @param id
     * @return
     */
    public Shop queryWithMutex(Long id){

        String lockKey = null;
        Shop shop = null;

        try {

            String key = CACHE_SHOP_KEY + id;

            //1.从redis中查询商铺缓存
            String shopJson = stringRedisTemplate.opsForValue().get(key);
            //2.判断缓存是否命中
            if (StrUtil.isNotBlank(shopJson)){
                //3.命中，直接返回
                return JSONUtil.toBean(shopJson, Shop.class);
            }
            //判断命中的是否是空值
            if (shopJson != null){

                return null;
            }
            //4.实现缓存重建
            //4.1.获取互斥锁
            lockKey = LOCK_SHOP_KEY + id;
            boolean tryLock = tryLock(lockKey);
            //4.2 判断是否获取成功
            if (!tryLock){
                //4.3 失败，则休眠后再重试
                Thread.sleep(50);
                return queryWithMutex(id);
            }
            //4.4 成功，根据id查询数据库
            shop = getById(id);

            //5.数据库中不存在，返回错误
            if (shop == null){
                //直接返回错误信息 会造成 缓存穿透
    //            return Result.fail("店铺不存在！");
                //将空值写入redis
                stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL,TimeUnit.MINUTES);
                return null;
            }

            //6.存在，写入redis
            stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        } finally {
            //7.释放锁
            unlock(lockKey);
        }

        //8.返回
        return shop;
    }



    /**
     * 查询店铺信息 （防止缓存穿透）
     * @param id 店铺ID
     * @return shop 店铺信息
     */
    public Shop queryWithPassThrough(Long id){
        String key = CACHE_SHOP_KEY + id;

        //1.从redis中查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断缓存是否命中
        if (StrUtil.isNotBlank(shopJson)){
            //3.命中，直接返回
            return JSONUtil.toBean(shopJson, Shop.class);
        }
        //判断命中的是否是空值
        if (shopJson != null){
            //返回一个错误信息
            return null;
        }

        //4.不存在，根据id查询数据库
        Shop shop = getById(id);
        //5.数据库中不存在，返回错误
        if (shop == null){
            //直接返回错误信息 会造成 缓存穿透
//            return Result.fail("店铺不存在！");
            //将空值写入redis
            stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL,TimeUnit.MINUTES);
            return null;
        }


        //6.存在，写入redis
        stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);
        //7.返回
        return shop;
    }


    /**
     * 获取锁
     * @param key
     * @return
     */
    private boolean tryLock(String key){

        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }

    /**
     * 释放锁
     * @param key
     */
    private void unlock(String key){

        stringRedisTemplate.delete(key);
    }

    /**
     * 把指定id商铺的信息(包含逻辑过期)写入Redis
     * @param id
     * @param expireSeconds
     */
    private void saveShop2Redis(Long id,Long expireSeconds){

        //1.查询店铺数据
        Shop shop = getById(id);
        //2.封装逻辑过期时间
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        //3.写入Redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id,JSONUtil.toJsonStr(redisData));
    }




    @Override
    @Transactional
    public Result update(Shop shop) {

        Long id = shop.getId();
        if (id == null){
            return Result.fail("店铺id不能为空");
        }
        //1.更新数据库
        updateById(shop);
        //2.删除缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY + id);
        return Result.ok();
    }

    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {

        //1.判断是否需要根据坐标查询
        if (x == null || y == null){
            //不需要坐标查询，按数据库查询
            Page<Shop> page = query()
                    .eq("type_id", typeId).page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            //返回数据
            return Result.ok(page.getRecords());
        }
        //2.计算分页参数
        int from = (current - 1) * SystemConstants.DEFAULT_PAGE_SIZE;
        int end = current * SystemConstants.DEFAULT_PAGE_SIZE;

        //3.查询redis,按照距离排序、分页。结果：shopId、distance
        String key = SHOP_GEO_KEY + typeId;
        //GEOSEARCH key BYLONLAT x y BYRADIUS 10 WITHDISTANCE
        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo().search(
                key,
                GeoReference.fromCoordinate(x, y),
                new Distance(5000),
                RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeDistance().limit(end)
        );

        //4.解析出ID
        if (results == null){
            return Result.ok(Collections.emptyList());
        }
        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> list = results.getContent();
        if (list.size() <= from){
            //没有下一页了
            return Result.ok(Collections.emptyList());
        }
        //4.1截取从 from 到 end 的部分
        List<Long> ids = new ArrayList<>(list.size());
        Map<String,Distance> distanceMap = new HashMap<>(list.size());
        list.stream().skip(from).forEach(result -> {
            //4.2获取店铺id
            String shopIdStr = result.getContent().getName();
            ids.add(Long.valueOf(shopIdStr));
            //4.3获取距离
            Distance distance = result.getDistance();
            distanceMap.put(shopIdStr,distance);
        });
        //5.根据id查询Shop
        String idStr = StrUtil.join(",", ids);
        List<Shop> shops = query().in("id", ids).last("ORDER BY FIELD(id," + idStr + ")").list();
        for (Shop shop : shops) {
            shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
        }
        //6.返回
        return Result.ok(shops);
    }
}
